Metal roofing with end wall of cement blocks

My daughter inherited an old brick commercial building. It has an addition on the back made of concrete blocks. It was covered with roll roofing and tons of sort of roof coating that has separated from the block and is in a curve on the end wall. I'm at the end wall now;; I have put sticks and new metal. I had to rip the last panel and will screw them curve up the existing wall.
My question is can I attach my self-made flashing to the side wall in the same screen hole as the up part of my panel? Using tapcon screws. This is my first metal roof alone and my very first time attaching to an end wall. I'm 65 and I have little money left to finish before it rains. Please help!! Thank you in advance!